The conventional internal combustion engines use pistons that move in a linear back and forth motion. This motion is transferred to a rotating crank shaft by a set of off-set bearings. Both the diesel and conventional gas engines are based on four cycles of intake, compression, ignition/expansion (or detonation), and exhaust. The two cycle engines most often have ports instead of valves, and combine the intake/compression cycles and the expansion/exhaust cycles. However, conventional engines tend to have relatively low efficiencies, large mass to energy ratios, and relatively large volume requirements, any of which where improvement is highly desirable. Furthermore, conventional engines tend to require relatively high RPMs to develop sufficiently high torque.
Some prior art engines that attempt to overcome some of these problems utilize a set of pistons that move around a toroidal chamber having a complex central shaft structure, using ports instead of valves and having a fixed main gear tied to the chassis and planetary drive gears that rotate around the main gear, while localizing the combustion in a part of the toroidal piston chamber. However, such a solution has the problem of localized high temperature spots and the strength of materials to transfer the high torque to the drive shaft.
Other engines are based on an earlier Morgan engine, using a rotating toroidal chamber (where the entire chamber spins) with pistons that oscillate. The torque is transferred to a crank shaft via a “Scotch yoke” tied to central co-linear cylinders that in turn are tied to the oscillating piston disks. Such engines have the problem of a large spinning toroidal chamber with electrical slip rings needed to carry the spark plug currents and a heavy Scotch yoke configuration to transfer the torque to the crank shaft.
The CO2 refrigeration cycle has attained recent renewed interest because of there are few, if any, environmental issues with its use. In this cycle, high pressure CO2 in its trans-critical phase is sent through an expansion valve to create a cold spot inside a refrigerator. The gas/liquid combination is warmed by taking heat from the inside of the refrigerator and becomes a vapor which is then pressurized by a compressor into its trans-critical phase. This compressed gas is cooled outside the refrigerator with ambient air, and then pumped into the refrigerator to the expansion valve to complete the cycle. By running the refrigeration cycle in reverse, it is possible to convert low quality heat (heat in the range of 300 degrees Celsius) into mechanical energy. In this reverse cycle, liquid CO2 is pressurize into its trans-critical phase, then heat is added to raise its temperature. Next the gas is put through an expander which cools the trans-critical CO2 and converts the high pressure gas energy to mechanical energy. Finally the gas is condensed back into a liquid, and the cycle is repeated. The theory of the expander system based on the CO2 cycle has been known for some time, but the missing element in this cycle is an expander which can be used with high pressure and low volume gas. Furthermore, improvements in efficiency, mass to energy ratios, and space volume considerations are also desirable.